Floorboard to firewall connection

[Bongo68]

Installing a tremec 500 in my 68 c10 and noticed alot of movement between the floorboard and firewall seam when I was measuring to cut floorboard. Question is was that seam just sealed or spot welded? If it was just sealed has anyone ever spot welded it? My game plane was to do both. Doing tranny mockup now but later on down the road will have to replace rocker pnls and typical floorboard rust along with this issue.